The present invention relates to crane safety methods and devices and, in particular, to improved safety devices and methods which warn workers of the movement of portions of a crane.
Conventional crane safety devices (e.g., U.S. Pat. No. 5,019,798) are subject to a number of deficiencies. For example, the devices must be manually attached to the load each time that a new load is secured to the crane. Further, a warning beacon on the safety device often becomes obscured by the load, especially where the load is large or of an unusual shape. Further, the warning indicators on the device are always active whether or not the load is actually in motion. This condition is dangerous because is does not sufficiently warn the workman when the ball is in motion. Because of these disadvantages, crane safety devices mounted proximate to the moving crane parts have not been widely utilized. Accordingly, there is a need for an improved crane safety device.
One aspect of the invention is to provide an acceleration sensor within the crane warning device which activates the crane warning device whenever the ball of the crane is being accelerated in any direction. For example, a mercury switch, a piezo-electric sensor, or other conventional acceleration sensor may be utilized to determine when the ball of the crane is accelerating.
Another aspect of the invention is to include a sensor which detects constant velocity motion of the ball of the crane. This sensor may be utilized in addition to or instead of the acceleration detector coupled to the ball of the crane. The motion sensor may be wholly contained within a housing of the warning device or it may be distributed at other locations in the crane such as by coupling portions of the warning device to one or more other electro-mechanical components of the crane. In one aspect of the invention, portions of the motion sensor are coupled to one or more hydraulic systems in the crane and actuated appropriately whenever the hydraulic system is actuated to move the ball of the crane. In yet other aspects of the invention, portions of the motions sensor are coupled to the electronic control system of the crane. In still other aspects of the invention, the mechanisms for detecting motion are mounted remotely and communicate with the warning device using electromagnetic waves such as radio waves.
In yet other aspects of the invention, fail-safe mechanisms may be built into the crane warning device such that the warning device is activated whenever a sensor fails or loses contact (e.g., radio contact) with the warning device. Further, a crane warning device status monitor may be built into the cabin of the crane so that the operator may be warned of any operational problems with any of the sensors in a timely fashion.
In still further aspects of the invention, the crane warning device may be mounted to maximize its utilization and resulting safety such as by integrating the crane warning device directly into the ball of the crane. In still further aspects, the warning device may be removably or fixedly attached to the side of the crane (e.g., by bolting or magnetically attaching the device to one or more sides of the counter weight).
In still further aspects of the invention, multiple crane warning devices are coupled to the crane in different locations so as to maximize safety. For example, one crane warning device may be located on the ball, and second, third, and/or fourth crane warning devices respectively mounted on first, second, and third sides of the crane counter weight. In yet other aspects of the invention, the audible and visual warning indicators from all of the crane warning devices may be synchronized such that the xe2x80x9cbeepxe2x80x9d noise and/or the strobe light from all of the crane warning devices are coincident.
In still further aspects of the invention, a microphone and speaker system is included in the crane warning device such that the operator can communicate with the workers. Worker safety is vastly increased because the worker may use both hands to manipulate the load while verbally signaling the operator. In further aspects of the invention, the a camera may be mounted such that a xe2x80x9cbirds eyexe2x80x9d view of the load/ball may be obtained by the operator sitting in the cab from a remotely mounted camera. The birds eye view, alone or in conjunction with the audio communications, vastly increases safety and efficiency of the crane operating environment. Additionally, in other aspects of the invention, electronics in the warning device may electronically filter the noise from the crane audible warning device so as not to interfere with normal communication with the crane operator. The filtering eliminates the beeping emitted from the warning device without filtering out the normal voice of the operator and/or worker. In still further aspects of the invention, the crane warning devices are mounted on different sides of the crane so that the operator has immediate communications with all sides of the crane, further enhancing safety.
Although the invention has been defined using the appended claims, these claims are exemplary and not limiting in that the invention is meant to include one or more elements from the apparatus and methods described herein in any combination or subcombination. Accordingly, there are any number of alternative combinations for defining the invention, which incorporate one or more elements from the specification (including the drawings) in various combinations or subcombinations.